1. Field of the Invention
The present invention relates to the suppression of viscosity in calcium exotoxin slurries and more particularly to the suppression of viscosity of such slurries by the addition thereto of certain copolymeric additives.
2. Description of Prior Art
In the latter stages of processing of various bioinsecticides by conventional techniques, a calcium exotoxin slurry is formed. This slurry contains, in addition to the desired calcium exotoxin bioinsecticide product, fermentation by-products, water, biomass, and various oils that served as food nutrients. The slurry then is concentrated by driving off water, often by ultrafiltration, to produce a product of lower water concentration and that is less expensive to transport. However, the viscosity of the slurry builds dramatically as water is driven off. Therefore, the degree of concentration that can be obtained without rendering the slurry too viscous to be worked practically is limited severely. The slurries rapidly become too viscous to be pumped or otherwise processed easily or conveniently.
As a result, the industry has been seeking a way to increase the concentration of such slurries further without increasing the viscosity thereof to unmanageable levels. Various chemical additives for reducing or suppressing viscosity have been tried, but none have been found to be sufficiently effective in reducing or suppressing the viscosity of the slurry. Accordingly, the industry also has been searching for a method for concentrating the slurry without increasing the viscosity to unmanageable levels that does not involve compositions or techniques that result in the frequent fouling of the ultrafiltration membranes that often are used to remove water from the slurry.